W32.HLLW.Qaz.A

Due to a decrease in submission rate, W32.HLLW.Qaz.A has been downgraded to a level 2 threat. W32.HLLW.Qaz.A was first discovered in China in July 2000. It is a companion virus that can spread over a network. It also has a "backdoor" that will enable a remote user to connect to and control the computer using port 7597. Because this virus cannot spread to computers outside of the network, it may have originally been sent by email. W32.HLLW.Qaz.A was originally known as Qaz.Trojan. It was renamed to W32.HLLW.Qaz.A on August 10, 2000. As of September 14, 2000, there are at least four variants of the original virus.

Also Known As:	Qaz.Trojan, Qaz.Worm, W32.HLLW.Qaz (gen), Worm.Qaz [Kaspersky], W32/QAZ.worm.gen [McAfee], W32/Qaz [Sophos], TROJ_QAZ.A [Trend], Win32.Qaz [Computer Associates]
Type:	Worm
Infection Length:	120320, 119296, 120297, 122880
Systems Affected:	Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
Systems Not Affected:	DOS, Linux, Macintosh, OS/2, UNIX, Windows 3.x

Virus Definitions (LiveUpdate™ Weekly) July 18, 2000 Virus Definitions (Intelligent Updater) July 18, 2000

Wild Number of infections: More than 1000 Number of sites: More than 10 Geographical distribution: High Threat containment: Moderate Removal: Moderate

Threat Metrics Wild: Low Damage: Medium Distribution: Medium

Damage

• Payload Trigger: Each time the virus is executed
• Payload: Creates a backdoor on the computer
  • Modifies files: Renames Notepad.exe to Note.com
  • Releases confidential info: Emails the infected computer's IP address to the hacker and also creates a backdoor to the computer
  • Compromises security settings: Allows unauthorized access to the computer

Distribution

• Ports: Listens for incoming TCP/IP connections on port 7597
• Target of infection: Notepad.exe

When W32.HLLW.Qaz.A is launched, it:

• Searches for and renames Notepad.exe to Note.com.
  
  
• Copies itself to the computer as Notepad.exe.
  
  Each time Notepad.exe is executed, it runs the virus code and the original Notepad, which was renamed to Note.com, to avoid being noticed. The virus adds the following string value:
  
  startIE   "notepad qazwsx.hsq"
  
  to the following registry key:
  
  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  

• Enumerates through the network neighborhood and attempts to find a computer to infect.
  
  When W32.HLLW.Qaz.A finds a computer, it infects it by searching for Notepad.exe and making the same modifications as previously described. The worm does not require any mapped drives to infect other computers. Once the computer is infected, its IP address is emailed to a remote user. The backdoor payload in the virus uses WinSock and awaits a connection. This enables a hacker to connect to and gain access to an infected computer.

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

The best way to remove this virus is to use the W32.HLLW.QAZ.A Fix tool.
If you cannot obtain the tool, see the following manual removal instructions.

Manual removal instructions
To manually remove this virus, you need to:

• Delete the virus's program files.
• Remove the startIE and bymer.scanner registry entries.
• Restore the original Notepad.exe file.

1. Run a full system scan, and delete any infected files.
2. Boot to MS-DOS mode, and then delete the virus-infected Notepad.exe and Note.com files, and in some cases, an infected copy of the Wininit.exe file.
3. Follow these steps to do this:
   
   Note: These instructions inform you about deleting the files in MS-DOS mode, because you must be disconnected from the network when deleting these files. If you are sure that you can restart the computer without connecting to the network, then you can delete the files in Windows using Windows Explorer.

1. After running LiveUpdate to make sure that you have the most recent virus definitions, run a full system scan, making sure that Norton AntiVirus is set to Scan All Files as previously described.
2. Delete any files that Norton AntiVirus finds that this virus has infected.
3. Click Start > Shut Down.
4. Click Restart in MS-DOS mode, and then click OK. The computer restarts in DOS mode, at the C:\Windows prompt.
   
   NOTE: This feature has been removed from Windows Me. If you are using Windows Me, you will have to use a Windows Me startup disk to boot to DOS. See your Windows Me documentation for information on how to do this.
   
   
5. Type the following, pressing Enter after each line:
   
   del notepad.exe
   ren note.com notepad.exe
   
   
6. Type the following:
   
   cd system
   
   and then press Enter. The prompt should now look similar to the following:
   
   C:\Windows\System>
   
   Important: In the next step you will delete a file. This file may not be found on all the systems infected with this virus. It is extremely important that you make sure that you are at the \Windows\System prompt and not at the \Windows prompt. A core Windows file with this file name is in the \Windows folder. If you delete the wrong copy, then you may not be able to restart Windows.
   
   
7. Type the following:
   
   del wininit.exe
   
   and then press Enter.
   
   
8. Restart the computer. Click OK if you see any error messages.

1. Click Start > Run.
2. Type regedit
   
   and then click OK.
   
   
3. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   
4. In the right pane, look for the following Name and Data:
   
   startIE "notepad qazwsx.hsq"
   
   Notes:
   • In most cases, the text in the Data column points to Notepad. A few cases have been reported in which it pointed to a different file. In either case, this entry points to the virus and must be deleted.
   • In some cases, this entry does not exist. If it does not exist, then skip to step 6.
     
     
5. Delete the startIE value. Click Yes to confirm.
6. In the right pane, look for the following value:
   
   bymer.scanner
   
   
7. If the value exists, select it, press Delete, and then click Yes to confirm.
8. Exit the Registry Editor.

Additional information:

Configure Windows for maximum protection
Because this virus spreads by using shared folders on networked computers, to ensure that the virus does not re-infect the computer after it has been removed, Symantec suggests sharing with read-only access or using password protection. For instructions on how to do this, see your Windows documentation or the document How to configure shared Windows folders for maximum network protection.

Write-up by: Motoaki Yamamura